Can You Estimate Body Surface Area Without Height?
Body surface area (BSA) is usually calculated with the Mosteller formula using both height and weight, but when you don't have your height handy or just want a quick ballpark figure, a simpler weight-only formula can help. This calculator uses (4×weight+7)/(weight+90) to give you an instant BSA approximation from weight alone.
When Is This Useful?
This formula was originally designed for quick pediatric BSA estimation and works well for tracking rough changes in BSA as weight changes, or in situations where entering height is inconvenient. It also shows how your estimate compares to the average adult BSA of about 1.7 m², giving you a sense of whether you're above or below that benchmark.
Need More Precision? Add Your Height
A weight-only estimate can be less accurate for body types that differ significantly from average. If you need precision for a medical consultation or detailed calculation, use a calculator based on the Mosteller or Du Bois formula that incorporates both height and weight.
Frequently Asked Questions
Yes, the quick formula (4×weight+7)/(weight+90) gives a fast approximation. It's less accurate than the Mosteller formula, which also factors in height.
Accuracy drops for people at extreme ends of the weight range. If you need a precise figure, use a calculator that includes both height and weight.
BSA reflects metabolic rate and blood flow more precisely than weight alone, which is why it's often used as a reference for drug dosing or burn area percentage in medical settings.